When semiconductor devices such as diodes, transistors, and the integrated circuits (ICs) which comprise either of the two, are exposed to ionizing radiation, such as gamma-rays or X-rays, electron-hole pairs are generated within the semiconductor material. These free carriers result in the generation of photocurrents as they are swept through the depletion regions of a p-n junction of the device or integrated circuit. The magnitude of these currents can be orders of magnitude greater than normal signal levels and can result in temporary or permanent system failure. Such photocurrent generation is generally referred to as a dose rate event.
When a photocurrent is induced, the electron free carriers will seek to be grounded, traveling through various circuit nodes until reaching a ground node. Similarly, hole free carriers will travel through an IC until reaching a power supply node. Because the magnitude of either the hole and/or electron currents may be quite large, permanent damage may occur as a ground node or a power supply node is sought out. For example, signal lines may be rapidly heated, via resistive heating, and fused together; high currents may rapidly decrease transistor performance (i.e., hot carrier effects); and, data states within the IC may be corrupted.